1. Field of the Invention
The present invention relates to a fluorescent member including particles which absorb excitation light emitted from a light source and convert a wavelength of the excitation light to emit lights of various colors. Particularly, the present invention relates to a fluorescent member having good light conversion efficiency and a good chromatic characteristic (with respect to shift of color), and a display device and an illumination device including such a fluorescent member.
2. Description of the Background Art
A fluorescent member including microcrystals or nano-crystals (or nano-particles) causing a quantum size effect shows excellent light conversion efficiency in conversion of excitation light into emission light different in wavelength. There is a possibility of obtaining a display device or an illumination device consuming less power by exciting such a fluorescent member with an ultraviolet light-emitting device. Japanese Patent Laying-Open No. 11-340516 discloses examples of such display and illumination devices.
In Japanese Patent Laying-Open No. 11-340516, a ZnCdSe mixed crystal which can absorb excitation light and emit red or green light, and a ZnSe crystal which can emit blue light are disclosed as particle materials to be included in the fluorescent member. The publication further discloses an illumination device and a display device in each of which the fluorescent member is excited by excitation light emitted from a nitride-based semiconductor light-emitting device.
The inventors have found, through detailed investigation of the optical characteristics of the fluorescent member including nano-crystals with respect to excitation light, that the light conversion efficiency, which is a ratio of the amount of light emitted from the fluorescent member to the amount of the excitation light, considerably varies depending on particle structure within the fluorescent member.